Cytomegalovirus (CMV) infection is common in humans, with seroprevalence rates reaching as high as 90% by adulthood. Although infection is usually asymptomatic in the normal host, CMV causes serious morbidity and mortality in immunocompromised cohorts, including transplant recipients and patients infected with HIV. CMV retinitis is a serious complication in patients with AIDS and profound immunosuppression. In addition, congenital CMV is the leading infectious cause of mental retardation and deafness in the United States. Current CMV therapies are effective in suppressing virus replication, but result in serious side effects, and the emergence of resistant viruses. Development of new compounds could significantly reduce morbidity and mortality from this pathogen. The overall goal of this application is to investigate the anti-CMV activities of artemisinins. Several artemisinin derivatives are widely used in malaria therapy. These compounds are orally available and have a good safety profile. The proposed investigation can be accomplished by our development of anti-viral assays and the availability of newly-synthesized artemisinin derivatives at Johns Hopkins University. We reported recently that dimeric artemisinins are dramatically more effective than the monomeric forms in inhibiting CMV replication in human fibroblasts. We have also shown that inhibition of CMV replication occurs at a very early stage of virus replication. The anti-CMV mechanism of artemisinins may be different than CMV inhibition by currently available compounds. We propose to identify the most potent anti-CMV artemisinin derivative, to evaluate whether combination with approved anti-CMV drugs is additive, and to elucidate mechanisms by which artemisinins inhibit CMV replication. This application is feasible and novel because we have acquired the experience and tools necessary for performing all experiments. For the first time we will use high throughput proteomics to identify the intracellular targets of artemisinins. The information derived from this application will have important impact on CMV therapy. It may lead to new concepts in CMV therapeutics by using a combination of compounds with direct anti-viral target and compounds which target a cellular protein that is important for CMV replication.